clk: stm32f7: add static for configure_clocks()

Also remove its declaration from stm32.h which
is no more needed.

Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
Acked-by: Vikas MANOCHA <vikas.manocha@st.com>

drivers/clk/clk_stm32f7.c

@@ -104,7 +104,7 @@ struct pll_psc sys_pll_psc = {
 #endif
 #endif
 
-int configure_clocks(void)
+static int configure_clocks(void)
 {
 	/* Reset RCC configuration */
 	setbits_le32(&STM32_RCC->cr, RCC_CR_HSION);